One of the more commonplace sites along many of the world highways is that presented by a towing vehicle such as a recreational vehicle, automobile or small truck having an attached trailer. Towing vehicles and trailer combinations are, of course, found in a variety of types and uses ranging from heavy industrial or commercial activities to lighter commercial and recreational activities. While heavy industrial trucks and larger commercial trucks readily employ trailer hitches to secure the trailer to the towing vehicle which are strong, reliable and extremely safe, their use has not extended into light truck, recreational and automobile towing apparatus due to the extremely large heavy structure and often unsightly appearance which they present. For the most part, recreational and light truck trailer hitches have comprised smaller less obtrusive and lighter structures.
The most common type of trailer hitch apparatus used in recreational and light truck towing activities is a ball and socket type trailer hitch combination in which the vehicle supports a rearwardly extending hitch member terminating in an upwardly extending ball support. The trailer includes a forwardly extending tongue element which supports a downwardly extending socket. The socket is received upon the ball and a lock mechanism operative on the trailer socket member secures the trailer tongue to the hitch ball in a ball and socket attachment. For safety purposes, a supplemental chain attachment is secured between the vehicle and the trailer to preclude inadvertent separation of the hitch. The object of the ball and socket-type hitch is to permit the necessary change in angle both horizontally and vertically which arise as the vehicle and its tow trailer negotiate turns and up and down hills or driveways or the like. In most trailer use, the hitch mechanism is subjected to substantial stress due to bumps in the road, abrupt turning activities or load shifting within the trailer.
It is well recognized by those using and regulating the use of trailer hitches to tow trailers that the separation of the trailer from the towing vehicle when the vehicle is in motion represents a potential for disaster. Thus, safety chains or similar safety apparatus are required by law in most industrialized nations of the world. However, a somewhat less well recognized potential for great harm in trailer towing operations is the loss of control resulting from trailer hitch separation notwithstanding the proper use of safety chains. Safety chains preclude complete separation between the towing vehicle and the trailer if properly used. However, once the hitch is separated, the chains do not provide control capability but merely loosely couple the trailer to the towing vehicle permitting wild gyration and motion as the vehicle driver attempts to bring the vehicle and trailer to a stop or otherwise avoid harm.
Because simple safety chains are recognized to be insufficient for complete security, practitioners in the art have endeavored to provide improved trailer hitch locks and safety mechanisms. For example, U.S. Pat. No. 4,428,596 issued to Bell, et al. sets forth an TRAILER SAFETY HITCH utilizing a ball and socket coupling together with a plate connected between the trailer tongue and the hitch member upon the vehicle. The plate is intended to coact with the ball and socket connection to prevent dislodgement of the ball from the socket. The plate defines a keyhole-shaped slot such that the plate can be placed on the hitch member and moved to a position which engages small portions of the keyhole slot. A pair of upwardly extending lugs are pivotally securable to the trailer tongue by a removable pin.
While practitioners have provided some improvement in the reliability and safety of trailer hitch combinations, the structures provided often restrict vehicle and trailer motion or fail to prevent theft or other undesired tampering. As a result, there remains a continuing need in the art for evermore improved safety and anti-theft featured trailer hitch structures.